How's kokanee fishing? It's a tricky question that relies on sound management and help from Mother Nature

Kokanee salmon are prized by Idaho anglers. In good years, stocking and management by Idaho Fish and Game, along with good environmental conditions, can create banner kokanee fishing. But within a few years, those same fisheries can turn belly up, which can be confusing – and frustrating – for anglers and fisheries managers because they value stable, reliable fishing. 

There’s a fairly complex, but important, backstory that helps explain the wild swings in kokanee fishing. Fish and Game biologists are constantly working with anglers to provide good kokanee fishing within the limitations of the fish’s life cycle and environmental conditions that drive them.

“Idaho traditionally has good kokanee fishing, and we expect that to continue in the future,” said Joe Kozfkay, Fish and Game’s State Fish Manager. “But we’re also facing some challenges that we want anglers to understand so they have realistic expectations about what we can provide.” 

Spoiler alert: the egg came first

To get a successful kokanee fishery, biologists take eggs from spawning fish, raise them to fingerlings, then plant those young fish in a suitable body of water where they can grow large enough for anglers to catch. Often, it’s that simple and works as expected. 

But let’s step back and better understand what actually drives kokanee populations. 

As most anglers know, kokanee are landlocked sockeye salmon. Unlike most salmon, sockeye (kokanee) are largely plankton eaters. Plankton are small, aquatic organisms barely visible to the human eye. Plankton abundance (or scarcity) is largely driven by environmental conditions, which vary from year to year. When plankton thrives, kokanee thrive, and the reverse is also true. 

Like their fellow salmon, kokanee are a “one-and-done” species that live about 3 to 5 years and die after spawning, so their populations are relatively short-lived and cyclical. 

Playing poker with an unknown number of chips

Since most Idaho waters have no connection to the ocean, most kokanee were originally stocked and thereafter became a self-sustaining population, or more likely, kokanee are restocked annually, or periodically, so managers can provide sustainable and fishable populations. 

In any kokanee water, biologists face a classic management question: Do anglers prefer fewer big fish, or more smaller fish? 

There’s never unlimited food in a body of water, so it’s always a tradeoff. Consistently achieving that balance is difficult because biologists don’t know how much food will be available from year to year. 

Water management is another important factor. Kokanee are often stocked in irrigation and flood-controlreservoirs, and rates of entrainment (fish lost through dams) can be high during high flows in the spring, or during irrigation drawdowns in the summer. Biologists can adjust the timing and locations of stocking to avoid entrainment, but they have no control over what happens to fish already in the reservoir.

To add complexity, biologists are uncertain each year how many young fish will be available for future stocking because they rely on a fluctuating number of adults from key waters to produce the next generation of fingerlings. Biologists, along with hatchery managers, can usually meet demand, but there are no guarantees, so sometimes managing kokanee is like playing poker when you don’t know how many chips you have. 

“We don’t want to give anglers the impression that we’re making excuses, and everything is in Mother Nature’s hands,” Kozfkay said. “Our fisheries managers have produced many, many successful years of kokanee fishing; but our early run broodstock populations aren’t where we’d like them to be, and this is going to negatively affect statewide stocking numbers until we can rebuild them.” 

It’s not just an Idaho challenge  

Kokanee are notoriously challenging wherever they swim, whether in Colorado, Wyoming or British Columbia, but the factors for fluctuating populations are generally the same in Idaho, including stocking numbers, young fish survival, food production and predators.  

Unfortunately, there’s rarely a “one size fits all” management approach for a successful kokanee fishery because each body of water has its own personality. Even reservoirs within the same watershed can behave differently, and they can all change over time. 

Let’s look at some examples around Idaho. 

Lake Pend Oreille

In the early 2000s, the kokanee population crashed in Idaho’s largest lake, and with it, a once thriving and popular kokanee and trophy rainbow trout fishery. Rather than a lack of food for kokanee, biologists identified the problem was too many predatory fish, primarily lake trout and the lake’s prized trophy rainbows. 

It was another case of biologists and anglers facing hard choices, and anglers making short-term sacrifices to improve fishing over the long term.

In order to recover kokanee, the balance between predators and prey had to be restored. This required removing large numbers of lake trout and rainbow trout. What followed was a large-scale management project that included Fish and Game paying anglers to harvest lake trout and rainbow trout, as well as netting lake trout to reduce their population.

After seven years of predator removal, kokanee returned to fishable numbers, and angler effort followed. That allowed Fish and Game to resume trophy management of rainbow trout, and those prized rainbows not only returned, the fish are reaching sizes that haven’t been seen since the early 1990s. 

Lake trout netting and incentivized angler harvest continues to keep predation in balance with kokanee populations. Predation management has proven to be very effective to sustain kokanee, and it will be an important part of managing the Lake Pend Oreille fishery into the future. 

Deadwood Reservoir

Remember how we mentioned the classic tradeoff between fewer big fish or more small fish? Fisheries managers have been wrestling with that for decades at Deadwood Reservoir. They’ve tried to find a happy medium for what is not only a popular, high-country kokanee fishing destination, since 1986, Deadwood also served as the primary egg source for early run kokanee.

 Deadwood’s history of having prolific natural kokanee production in its tributaries, and an overabundance of smaller kokanee, made it an ideal egg source for early run kokanee. Limiting the natural spawning not only helped fill Fish and Game’s hatcheries with early run kokanee fingerlings that supplied up to 20 other waters, it also made Deadwood a more desirable kokanee fishery because it raised the average size of the fish.

Around 2019, something changed at Deadwood. Fish and Game surveys detected a steep decline in kokanee numbers coming up the Deadwood River to spawn. Biologists also found that despite low numbers of kokanee, fish sizes were smaller than expected — bucking the typical pattern of larger kokanee when there’s a smaller population.

In the years since, biologists have ramped up monitoring the fishery, and kokanee sizes and densities have both remained low. 

“We’ve taken a look at many factors that might contribute to decreased kokanee numbers without a concurrent increase in sizes — including predation, food limitations and water quality — and we haven’t found a smoking gun, yet,” said Regional Fisheries Biologist Tim D’Amico.

Although the answer to “why” remains elusive, fisheries managers have worked to help kokanee rebound at Deadwood by foregoing egg take from the reservoir for the last two years to maximize natural production, and even stocking additional kokanee fingerlings (sourced from eggs taken at Payette Lake) to give the fishery a boost. 

Payette Lake

This deep, clear lake is fed mostly by snowmelt from granite mountains, which means limited food available for other fish. Those conditions can provide good habitat for plankton-eating kokanee because they have few competitors. 

In the mid-1990s, kokanee thrived in the lake, and during fall, the North Fork of the Payette River above the lake ran red with thousands of spawning kokanee. In the early 2000s, lake trout population increased substantially, which in turn crashed the kokanee population, and the wave of spawning redfish slowed to a trickle. 

Taking a page from Lake Pend Oreille’s playbook, biologists in 2014 began significantly reducing lake trout numbers, and in 2020, they started boosting kokanee by heavily stocking fingerlings. The results were almost instant. 

By 2022, anglers were enjoying good kokanee fishing during summer, and in 2023, anglers harvested about 8,000 kokanee with another 3,000 spawning adults swimming up the North Fork and providing eggs for future stockings. 

This is a short-term success, and time will tell if the upswing is sustainable, or part of a boom-and-bust cycle, but things are looking promising for Payette Lake’s previously dormant kokanee fishery. 

Lucky Peak, Arrowrock and Anderson Ranch reservoirs

These three irrigation reservoirs in the Boise River Basin are linked to each other and receive lots of kokanee fishing effort, but they’re each managed differently. 

Anderson Ranch is the farthest upstream of the three, which flows into Arrowrock, which then flows into Lucky Peak. Anderson Ranch receives stocked hatchery kokanee, and the tributaries feeding into Anderson Ranch have naturally spawning fish, which is the only of these three reservoirs with significant natural production. Because of that, Anderson Ranch has a 15-fish kokanee bag limit rather than a 6-fish limit at Lucky Peak and Arrowrock.  

The fisheries at Arrowrock and Lucky Peak are driven by Fish and Game stocking and supplemented by limited natural production and entrainment (kokanee flushing through upstream dams).

Entrainment can provide challenges for fisheries managers because it varies from year to year, and it can affect kokanee fishing because too many unexpected fish in a reservoir can mean too many mouths to feed for the food available, which in turn affects average fish size and angling success. Biologists estimate that in some years, up to 80% of kokanee stocked into Arrowrock end up in Lucky Peak. 

At Lucky Peak and Arrowrock, the number of anglers typically corresponds with average fish size. Angler effort increases when kokanee sizes are larger, which tends to drive up catch rates as well.

Biologists are working to better understand the variations in entrainment from year to year. Since 2020, they have marked hatchery-raised kokanee in hopes of tracking age-specific entrainment of kokanee within the three-reservoir system to learn how it affects each reservoir. 

Is captive broodstock a solution for stability?

In addition to rebuilding traditional wild broodstock, fisheries managers are exploring alternatives for getting more kokanee eggs each year so they can start each stocking cycle with a predictable number of fingerlings. 

Taking eggs from adults raised in the wild is the most cost-effective way to replenish hatcheries and later stock lakes and reservoirs with fingerlings. One strategy includes taking spawners from more water sources because Fish and Game biologists prefer to rely on that method. 

But back to the poker analogy. They’d also like to stack the deck to ensure they have enough fingerlings to stock each year. 

Another strategy to avoid uncertainty is Fish and Game could grow some kokanee to adults in hatcheries specifically for spawning. Coincidentally, this strategy – known as “captive broodstock” – is what kept Idaho’s ocean-going sockeye from going extinct. 

But again, there are trade-offs to this approach. 

Hatchery managers don’t know how well kokanee will survive their entire lives in a hatchery, or if their offspring will be equally fit to survive and grow to catchable sizes after being stocked. Plus, it costs more, and most Fish and Game’s hatcheries are running at capacity, so raising kokanee would mean less space available to raise other important game fish.

Biologists want anglers’ input (but sorry, you can’t have lots of big kokanee every year)

Anglers play an important role in many of these decisions. As examples, Fish and Game plans to try raising broodstock in hatcheries to provide more consistency, but would anglers be willing to trade a smaller bag limit in some waters to ensure more adults become spawners for the next generation?

Maybe anglers would prefer having kokanee in fewer waters that have a history of producing good fishing rather than spreading those limited fingerlings across more waters that have other game fish available, or simply don’t have a history of producing good kokanee fishing. 

And anglers have to be realistic with their expectations. There is no magic formula for great kokanee fishing, and that amazing summer you had catching lots of big kokanee may have actually been a warning sign that the overall population was headed in the wrong direction. 

So yes, we’d all love to have lots of big kokanee every year, but that’s not how cyclical kokanee populations function. 

Meeting anglers’ expectations (or trying) through informed and adaptive management

The final chapter of Idaho’s kokanee management will never be completely written because as it has changed in the past – for better and worse – it will change again.

Biologists will continue to learn through science, research and experience, and they will adapt Fish and Game’s management to changing conditions while using angler preferences to help guide Idaho’s kokanee fisheries into the future.